Automatic cut-off



(No Model) 2 Silesia-Sheet l f E. THOMSON. AUTOMATIC GUT-OFF.

110.360.12 1. V Patented Mar. 29, 1887.

INVENTOR A TTORNE Y n. PETERS. Phmmutho raphlr. Wahingm no (No model.) Sheets8heet z.

E. THOMSON.

AUTOMATIC GUT-OFF.

Patented-Mar. 29, 1887.

I INVENTOR v 2 6 I UNITED STATES PATENT OFFICE.

ELlHU THOMSON, OF LYNN, MASSACHUSETTS.

AUTOMATIC CUT-OFF.

SPECIFICATION forming part of Letters Patent No. 360,124, dated March 29, 1887.

Application filed September 6, 1886. Serial No. 212,768. (No model.)

To aZZ whom it may concern:

Be it known that I, ELIHU THOMSON, a citizen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented a certain new and useful Automatic Electric Cut-Out for Series Lamps, of which the following is a specification.

The present invention is an improvement upon the invention described and claimed in a prior application filed August 25, 1886, No. 211,851, in which a peculiar differential magnet and contacts are used to shunt an incandescent lamp when it offers either too high or too low a resistance to the current. Suchlamps are run in series on lines of constant current or branches from mains, in which branches a constant current is maintained.

My present invention is designed to obviate the use of the dash-pots or contact-holding mechanism of my former case referred to.

It consists in the use, in conjunction with the coil in the main circuit or lamp-circuit and the coil in the derived circuit to the lamp acting differentially to close a contact, of a third coil in the circuit, only brought into action upon the closure of the shunting contacts, and thereafter acting to re-enforce the contact-closing action of the coil in the main circuit or lamp-circuit, as stated.

The object secured is to keep said contact closed, even though the magnetism of the differential combination is reversed at the moment of closure. This result is secured in my former case by dash-pots and peculiarly-constructed contact operating mechanism controlled by the magnets.

In the accompanying drawings, Figure 1 shows an arrangement of devices embodying my invention. Fig. 2 is a diagrammatic representation of the connections and winding. Fig. 3 shows a mode of winding the coils. Figs. 4, 5, 6, 7, and 8 show modified forms of combining the action of the coils. Figs. 9 and 10 are detail views.

In Fig. 1, a is a connection from a constantcurrent line through to b and onto the line. A

switch, S, serves to effect a direct shunt from a to b. When S is open, the connection from a to b is normally as follows: From a a wire leads to one terminal of a lamp, L, whose carbon conductor or filament connects the wires, as usual. The other terminalof the lamp is connected by a wire to an upper or fixed contact at M, and thence through the coil 0 to line b. A connection from a to I) through the fine-wire coil K exists as a high-resistance derived-cin cuit coil. by currents in opposite directions around the magnet-core upon which they are wound, and the ampere turns are nearly equal in each when the lamp L is of normal resistance and the current on the line is standard. In addition to these coils, there is a third coil, 0, normally open-circuited, but which comes into circuit when the armatureA is attracted and the contact at M is closed. One end of the coil 0 is attached to the main line a, and the other end is in connection with the lower contact at M, moved by the armature A, as shown. The direction of flow of current being the same as in 0, through the coil 0, therefore re-enforces the coil 0 in its action on the armature A.

The operation is as follows: On opening the switch S, if the lamp L is of normal resistance, the magnetic power of the coils O and K will be nearly equal and opposite in direction, so that the coils will neutralize each other so faras their action upon the armature A is concerned. Under these conditions, therefore, there will be no movement of the armature. When, however, the lamp is of abnormally-low resistance, or becomes so during burning, or a partial short-circuiting takes place between its terminals, thecoil K will lose in energizing power and fail to balance the attractive effect of the coil 0. The armature A then rises, closes contact at M,whereby alow-resistance path is opened from wire a, through the coil 0 to contact M, and from there through coil G to line b. The coils G and 0, however, reen'force each other and hold the contact M firmly closed. XVhen an abnormally-high resistance exists from one terminal of the lamp to the other, the derived-circuit magnet K becomes abnormally strong, overcomes the opposing effect of the current in G, lifts the armature A, and closes the contact at M. At this instant the coil K loses its power, being shunted by the low resistance of the coils O and O, of coarse wire. The magnetism of the core instantly reverses and holds M closed The coil K and coil 0 are traversed by the current in O and G, as before. \Vere the coil 0 alone acting at the moment of this reversal, the armature A would have time to drop away and open an are or bad spark at M but the re-enforcing of the coil 0 by the power of the supplementary coil 0, working with it to reverse the magnetism and hold the c011- tact, prevents such damaging result. Hence, should a breakage of filament F occur, giving rise to a resistance between the lamp terminals much different from the normal lamp resistance, the lamp will be cut out, as described, by the contacts M closing and remaining closed. The switch S, when closed, shunts G and C, so causing the armature A to drop and contacts M to open.

In Fig. 2 the winding of Fig. 1 is displayed in outline for elearness, same letters representing similar parts.

It is not necessary to wind the coils as shown in Fi 1; but they may be wound concentrically one over the other, as indicated in Fig.3; or three coils acting on the same armature, though wound on separate cores, may be used, as in Fig. 4, it being understood that the pole of the coil K, presented to the armature, will be the same as the pole-say north-presented by the coil 0 to said armature, so as to obtain the differential effect of the two. Again,

as shown in Fig. 5, the coils K and 0 may be wound 011 the same core and the coil 0 upon the armature. Again, as shown in Fig. 6, the coils K and 0 may be solenoid-coils, the core being wound with the coil 0. In this instance the core and coil should, if they are the movable elements, be counterpoised or balanced (nearly) by a weight or spring to secure sensitiveness to small changes of pull in coil K.

In Fig. 7 the coils K and C are wound differentially on a core, the armature A being used to close contact, as before but the upper contact is made movable toward the lower by an armature, 13, of a magnet upon which coil 0 is wound. Thus when armature A is attracted to close contact (by either K or O) the coil 0 is thereupon energized to bring the upper contact down and hold the contact closed during reversal of magnetism in the differential niagnet-core. Other forms of differentially-acting magnet systems are easily adapted to my invention. Thus in Fig. 8 the coil K is wound on the core of a magnet, while the coil 0 is wound upon a core which virtually is the armature of magnet K, the current being made to circulate oppositely in K and C, so that they may present like poles toward each other; but should either so far preponderate in power as to cause attraction the contact M is closed, consequent upon which action the magnet C is energized and attracts B, its armature, to hold contact M closed.

It is advisable, where the resistance of the lamp L when cold much exceeds its normal resistance when hot, that the shunt-switch S be opened gradually,so as to give time for the resistance of the lamp L to fall to the normal before the cut-out is actuated. This may be accomplished by causing the switch to insert resistances at R, Fig. 9, in its own path as a shunt just before opening such shunt from a to 1). Another arrangement is to cause the hue wire magnet K to be given its normal power only after the switch S has been opened for a short interval.

In Fig. 10 the connection from a to b,throngh coil K, is made to include a resistance, It, which, when the switch Sis opened fully, is shunted by the switch touching a cont-act at It, just after opening the connection from a to Z).

Other similar devices insuring asmall interval of passage of current through the lamp before K attains full power will suflice for the. purpose. Such a safeguard is only needed' Where the adjustments are finely made, and where at the same time the resistance of the lamp is greatly diminished in amount as the current is thrown on and requires a moment or two to heat its carbon to incandescence,and where the current might be very suddenly applied,thus giving undue energy to the derived circuit K, which might provoke a premature cut-out of the lamp.

Vhat I claim as my invention is- 1. Theconibination, with an incandescent lamp or other translator of electric energy, of a differential magnet made up of opposing coils in the main circuit, and in a derived circuit around the translator, ashunting contact controlled by such magnet, and a re-enforcing coil inserted into the main circuitby the shunting contact in closing, said re-enforeing coil tending to holdsuch contact closed, as and for the purpose specified.

2. The combination, with an incandescent lamp or other translator of electric energy, of a differential magnet, an armature, core, or equivalent device responding to the differential action of such magnet to close a shuntingcircuit around said translator, and a re-enforcing coil inserted into the main circuit by the action of such core or armature in closing the contact, as and for the purpose set forth.

3. The combination, with an incandescent lamp or other translator of electric energy, of a coil in the main or leading circuit, a coil in a derived circuit around the translator, a device responding to the differential action of such coils to close a shunting-circuit around the lamp or other translator, and a re-enl'orcing coil inserted into the main circuit by the action of such device to re-enforce the action of the main cireuit coil, as and for the purpose set forth.

4. The combination, with an incandescent lamp or other translator of electric energy, of a differential magnet made up of coils in the main or leading circuit and in a derived circuit around the translator, an armature, core, or equivalent device adapted to close a shunting-circuit around the translator when either coil predominates in magnetic effect, and to hold such contact closed by the action of the coil in the main circuit, and a rc-cnforcing coil inserted into the circuit by the action of such core or armature and adapted to re-enforce the action of the main coil, as and for the purpose described.

5 5. The combination, with an incandescent lamp or other translator of electric energy, of a coil in the main and an opposing coil in a derived circuit around the translator, said coils being normally counterbalanced and adapted to close a shunting contact upon the preponderance of either coil, and a switching mechanism adapted to insert resistances in its own path as a shunt just before opening such shunt, as and for the purpose described.

'. r5 6. The combination, with an incandescent a derived circuit around the lamp, a shunting contact controlled by the differential action of such coils, and means for letting the current onto the lamp-circuit gradually, as and for the purpose described.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 31st day of August, 4 5 A. D. 1886.

ELIHU THOMSON. Witnesses:

J. W. GIBBONEY, Geo. W. Dnvnnronr. 

